Quite numerous: Armagh, Meath etc. Ir. Ó Caorthannáin, caorthann, rowan-tree. The name is English but in Ireland 14 cent. It is now a Yorkshire name, usually Rowntree.

Rowantree:

rare: Down etc. See Rowntree.

Rowntree:

fairly rare: Armagh-Down-Monaghan. Evidently an English name, it appeared in Oriel (Armagh-Monaghan) in 14 cent. It now occurs as Rowantree, Rountree, Roundtree and in Irish, by translation, Ó Caorthannáin.SI.